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Help for dtdisplay: Control area
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<H3>dtdisplay on-line help</H3>
<H1>Control area</H1>
Along the left side of the main window below the menu bar is a control panel.  The panel 
contains a scrolled text output area, text fields to change the detector position and 
wavelength and buttons to move to the next or previous image in a scan.
 
<dl>
<dt>Scrolled Text Output
<dd>	The scrolled text output is a flexible way to provide information about points 
selected in the large image display area.  When you select pixels in the large image area, 
the information in the scrolled text area usually contains:
<p><pre>
        Pixel position
	Pixel value
	Millimeter position
	Resolution
	Integrated intensity and standard deviation
	Average background and standard deviation
</pre>
<p>
If the Measure toggle button in the View menu is set, then the crystallographic d-spacing 
between the selected pixel and the previously selected pixel will be reported.  The 
information reported does depend on a number of factors.  The millimeter position, 
resolution and d-spacing all depend on knowledge of the detector position, the detector 
spatial distortion and the source wavelength.  If this additional information is unavailable, 
then millimeter position, resolution and d-spacing will not be reported.
<p>
Use the scrollbar to scroll the output backwards and forwards.  The output may be cleared 
by first selecting it and then choosing the Clear selected output command from the Edit 
menu.
<p>
<dt>Rot. start, Rot. end
<dd>	Enter the rotation start angle and end angle for the image.  Presently, these have 
no effect.

<dt>Det swing
<dd>	Enter the desired detector swing angle in degrees.  The direction of the swing axis 
is specified in the header and is usually the theta or 2theta value of the detector.  Use this 
command to check the resolution limits at a particular detector position.  The starting 
value for the swing angle is read from the image header.  The value is updated only after a 
carriage return or when the text field loses input focus.

<dt>Det dist
<dd>	Enter the desired detector to sample distance in millimeters.  Use this command to 
check the resolution limits at a particular detector position.  The starting value for the 
distance is read from the image header.  The value is updated only after a carriage return 
or when the text field loses the input focus.

<dt>Wavelength
<dd>	Enter the wavelength in Angstroms. The value is updated only after a carriage return or when the text field loses the input focus.
<dt><b>NOTE:</b>
<dd>If you changed the detector distance or swing angle or the wavelength, then
the minimum and maximum resolution available on the detector is displayed in
the scrolled text output in the upper left of the main window.

<dt>Prev, Next, No.
<dd>	These commands let you easily select the previous image, the next image or a 
specific image sequence number in a scan to read in and view.  If a scan definition is not 
found in the image header, then these commands should be insensitive.  You may specify 
your own scan definition with the <A HREF=FileMenu.html>Image template... </A>
command in the File menu.  When 
an image is read with the Prev, Next or No. commands, the mapping of pixel values to 
colors is not changed, but the current mapping is used.  If an error occurs when reading 
the image file, then the image display areas go blank.

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